Wastewater treatment facilities are found around the world and many are located in areas where the temperature of the water treated varies with the seasons. Many of these facilities are facing regulatory pressures to reduce the amount of fixed nitrogen discharged. To meet stringent discharge requirements, wastewater facilities are typically designed to perform during cold weather conditions. The biological organisms used by these facilities to treat nitrogen compounds are affected by temperature: nitrification and denitrification organisms are more effective at temperatures between 25° C. and 30° C. and less effective at temperatures between 8° C. and 12° C.